Advice on gravel needed

[Flyfisher]

Interesting piece on the radio this morning about a new decision not to build a severn barrage (I'm sure that project has been on/off since I was at school!) even though our recent electricity generation hit the record high of 50%-from-gas figure recently. Apparently the numbers makes it uneconomic at present so, presumably, they think we still have loads of fossil fuels to get through. The report also touched on the current waste of a lot of "weather-generated" electricity due to a lack of storage capability, thus a good spell of windy weather overnight is almost entirely wasted as the 'base-load' of generation from fossil fuels is more than enough for night-time demands. Hydrogen generation using the surplus electricity was mentioned in passing as a possible solution but there were no details.

Biff, would you mind sharing the basic numbers of your rather impressive PV array? It would be interesting to know the capital cost, the average amounts generated and the rate of payback based on either your consumption savings and/or feed-in payments.

 

[Penners]

Hydrogen generation using the surplus electricity was mentioned in passing as a possible solution

The Dinorwic pumped storage scheme in north Wales (with whose construction I was indirectly involved) offers an interesting way to store energy, when surplus electricity is available.

Water is stored in a mountain-top lake. At a lower level there are hydro-electric turbines, inside the mountain. In the valley below is the bottom lake.

In periods of high electricity demand, water is released from the top lake, turns the turbines and flows into the bottom lake. During periods of low demand (eg: the middle of the night) surplus power is used to pump the water back up into the top lake.

I was amazed to hear of the cancellation of the Severn Barrage scheme. I simply don't understand why we are throwing money at wind energy projects, when wind is a variable resource. Likewise, waves are a variable resource. But tide is utterly reliable.

Today, we can foretell the rise and fall of the tides for the indefinite future because we know that, whatever else may befall us, they can be relied upon to rise and fall for evermore. But wind and waves come and go. We have no idea of their performance next week, next month ... or ever.

It seems crazy not to concentrate our efforts on harnessing this endless and ceaseless resource.

 

[biffvernon]

Is that the right link Biff?

Absolutely not! Try this: http://www.transformeddriveways.co.uk/default.php

 

[biffvernon]

a good spell of windy weather overnight is almost entirely wasted as the 'base-load' of generation from fossil fuels is more than enough for night-time demands.

Trouble with that is it's just not true!

Biff, would you mind sharing the basic numbers of your rather impressive PV array? It would be interesting to know the capital cost, the average amounts generated and the rate of payback based on either your consumption savings and/or feed-in payments.

Cost £14300 3.96kWp from 22 x 180W Yingli modules and SMA inverter, so about £3.61p per kWp

Average generation for the last 5 weeks has been 8kWhr per day (and it's been unusually cloudy). We're on track to meet the government inspired generation projection. Feed in Tariff is 41.3p per unit plus 3p per unit for the 50% of deemed export plus the savings on what you don't buy on sunny days makes every unit generated effectively worth about 50p. Modules are guaranteed to last 25 years. Assume that the inverter will die and need replacing once in that period.

Should see a return on capital of ~9%

I got quotes from several firms and went with http://www.ethicalsolar.org/ because they were both the cheapest and the bloke who runs it, John Whiten, is a nice guy. The work was completed quickly and efficiently with everything done as promised. I can recommend this firm.

 

[CatherineB]

River? I know a little. It's almost certainly a non-starter for several reasons, but there are circumstances where it is viable. Tell me more about your river.

Now, back to the gravel. Somebody has asked me what I think about this: http://preview18.838888.co.uk/Clients/ltp/

My response is probably unprintable ....

But Biff, it's "specified by English Heritage" - so it must be ok! :mrgreen:

 

[CatherineB]

While remaining shamefully ignorant on all these things, I too am extremely disappointed that the Severn barrage has been cancelled due to cost considerations. How feeble is that, and what a poor legacy to future generations, if we're really saying "well we know it's the right thing, and we'd like to do it, but we just don't think it's worth the money"... I'd get rid of a few more quangoes myself, but there you go :roll:

How can it possibly be preferable to use fossil fuels as the "base load" supply and treat renewables as extras; surely that destroys the point that we're trying to use less fossil fuels? Someone please tell me the solar water system I'm thinking of installing doesn't work this way, please! :?

 

[skier-hughes]

What's the square meterage of panels?

 

[Flyfisher]

a good spell of windy weather overnight is almost entirely wasted as the 'base-load' of generation from fossil fuels is more than enough for night-time demands.

Trouble with that is it's just not true!

It's what they said on that programme this morning. I accept they could be wrong but the reasons why would be helpful.

How can it possibly be preferable to use fossil fuels as the "base load" supply and treat renewables as extras; surely that destroys the point that we're trying to use less fossil fuels? Someone please tell me the solar water system I'm thinking of installing doesn't work this way, please! :?

As I understand things, storage is the issue, something that's not easy with electricity. Solar water heating systems store the daytime heat in a large water tank for release during the cooler evenings, so very little wasted energy. From what I've read, solar water heating is one of the more efficient renewable technologies.

Penners' mention of the Dinorwic pumped-storage system is relevant here (according to wiki it's about 74% efficient - higher than I would have guessed) but such schemes are not common, so in general the amount of electricity produced is more than we need but the industry spends a lot of time and trouble to try to minimise this over-generation.

The last figures I saw showed renewables contributing 6% to the UK generating base, although I don't know if that's a total capacity figure or an actually-used figure. Being such a low figure, storage is probably less of an issue at present, but if renewables become a significant portion of our capacity then storage or demand-management will become a much bigger issue.

But, as mentioned above, surely the reliable tides would be a better source of energy than unreliable winds. I recall the radio report this morning stated that the severn barrage would generate the amount of power required by the whole of wales. How many wind turbines would be required to guarantee a similar capacity?

 

[Penners]

the severn barrage would generate the amount of power required by the whole of wales. How many wind turbines would be required to guarantee a similar capacity?

I have no idea, but I'd put money on the area covered by them being substantially greater than the area affected by the Severn Barrage.

 

[TomW]

The Severn barrage would have been an ecological disaster.
What is the point of green and renewable energy if it destroys the very environment we're all so keen on saving?

 

[Flyfisher]

Yes, I heard the FotE chappie on the radio this evening talking about the impact on wading birds, but your (very pertinent) question works both ways. Trade-offs are never easy but perhaps trading off the severn estuary in return for clean, renewable energy for the whole of Wales might be worth the decline of some wading bird numbers?

Anyway, it's a bit academic now that the decision is made (for the next 4-5 years anyway) and the favoured way forward appears to be more nuclear and more coal (with carbon capture of course :roll: ) power stations.

 

[biffvernon]

Electricity storage from the wind turbines is a very long way from an issue. It's a non-problem. Any wind generated electricity surges, no matter what the time of day, can be used to substitute for gas and thereby reduces carbon emissions and balance of payments issues over buying Norwegian and Russian gas.

Dinorwig is not primarily about storing surplus energy but more about fine-tuning the load following capacity of the grid. The turbines can reach full speed even faster than in a gas power station. 75 seconds from a standing start or, with the six turbines spinning in air and sychronised, can get from zero to 1800MW in 16 seconds.

It was originally built as a way to use spare nuclear base load power but the smaller than planned nuclear fleet has meant that this function has been superseded by the fast reaction load following.

 

[biffvernon]

What's the square meterage of panels?

1310mm x 990mm = ~1.3m^2 each
~28.5m^2 for 22 of them.

If you have plenty of roof space it makes sense to go for the greatest output per £ rather than per square metre. The most 'efficient' modules are not the best value for money unless your roof space is constrained.

 

[skier-hughes]

As some of my roof now contains Solar hot water panels, I don't have a great area left for Solar PV. I'll have to have a calculate, thanks.

 

[biffvernon]

The Severn barrage would have been an ecological disaster.
What is the point of green and renewable energy if it destroys the very environment we're all so keen on saving?

There's no simple answer to that one. The loss of habitat and bird numbers is likely to be much greater if we burn coal than if we don't.

I do think it is a pity that inadequate consideration has been given to the lagoon idea. Still, this barrage was never going to help with the power shortage during the lifetime of this or the next parliament. It was only the Victorians who took a longer view.

 

[Flyfisher]

Should see a return on capital of ~9%

Thanks for that info Biff. I had a quick play with a spreadsheet and your 9% figure looks rather conservative, especially considering the 5 week cloudy sample period for the 8KWh/day generation figure. It's all down to that feed-in tariff figure of course - is there any sort of contractual commitment to that or could the government just cancel it tomorrow? It surely can't be a sustainable figure if everyone followed your laudable example. How does it work in practice - quarterly meter readings wth a cheque received rather than paid out?

Definitely food for thought.

 

[biffvernon]

Yes the 9% figure is conservative but I'm like that when it come to money!

There's been a lot of talk about commitment to the FIT. That I'm going to get 41.3p index linked per unit for 25 years is about as copper-bottomed as anything is. Governments tend not to break contracts and the cash is actually paid by your electricity supplier - it's a levy on the power industry - not from the Treasury, so there's little incentive for the Government to pass legislation to change it. What is in doubt is the commitment to keep the FIT in place for future adopters. That's has worried the solar industry, whose members have invested millions in tooling up for expansion and have threatened to sue the Government should they change the policy in the future.

Of course it's not sustainable if everybody adopts but there are some stiff hurdles. Not everyone has a spare ~£15 grand or a suitable roof or is confident they will get the benefit by not moving house (though it ought to up the house value and the FIT stays with the house). On the other hand the Government is signed up to legally binding renewables obligations with expensive fines if the targets are not met. Any Secretary of State for Energy and Climate Change must feel between a rock and a hard place, a tricky position created by Ed Miliband, the previous incumbent.

 

[Schoolmarm]

There are companies who will fit them to your roof and take the FIT payments. Sort of renting your roof.

They must think it is worth it.


http://blogs.telegraph.co.uk/finance/ianmcowie/100007449/how-the-roof-over-your-head-could-earn-1000-out-of-thin-air/

 

[biffvernon]

Very bad deal that - someone else makes a lot of money out of your roof.

However, Ecotricity has just launced a four year bond paying 7%. That really is way above the market rate. There are not many places where you get much over 3% at the moment.

Summary Of Terms

Main Terms:

Subscription in multiples of £500;
Maturity: 4 year initial term. The EcoBonds may be redeemed in full upon the Bondholder giving six months notice prior to the fourth anniversary or any subsequent anniversary;
Coupon: 7% per annum. Bondholders who are also Ecotricity customers on the future interest payment dates, and were in the preceding six months will receive an additional 0.5% per annum
Security: EcoBonds are an unsecured debt of the Company. The repayment obligations of the Company have been guaranteed by Ecotricity Group Limited; and
Use of Proceeds: UK renewable energy projects and general corporate purposes in relation to the expansion of Green Energy generation and supply.

7% is not so very far off the ~9% return one might expect from solar pv with FIT. But it works on north-facing roofs.

It's an unsecured debt so one has to be confident that Ecotricity won't go bust.

http://www.ecotricity.co.uk/ecobonds/introduction-from-dale-vince

 

[Schoolmarm]

I only posted the link to show that there is money to be made if firms want our roof space.